Ask a Chemist: What is Encapsulated Vitamin C?

Our Head of Chemistry, Lizzy Trelstad, weighs in on your most pressing skincare questions.

Vitamin C is notoriously hard to stabilize in a formula. It dissolves easily into an aqueous solution but then immediately starts to do what it does best: interact with ambient light as an antioxidant. The tell-tale sign of early oxidation is a yellowing or browning of the ascorbic-acid (AA) solution. This discoloration indicates  there's little-to-no remaining AA left in the formula ready to work with/on your skin.

The formulator's goal is to dissolve the AA into the solution, and then chemically or mechanically "freeze" the molecules such that they can save their antioxidant power for your skin. One technique of freezing or slowing the kinetics of AA is to "encapsulate" it. Encapsulation involves building a cage out of polymers, injecting and trapping AA into said cage, and suspending the spheres (i.e., the cages) in the formula. The theory is that the AA will stay trapped in the copolymer spheres until the formula is applied to your skin, at which point heat and friction motivate the AA to slowly diffuse out of spheres and onto your skin. Another, though weaker, encapsulation technique involves cages that physically break open with friction and heat, causing the AA to gush out. 

Some encapsulations are made out of a complex of emulsifiers and stabilizers, like polyglyceryls. More sophisticated encapsulations are normally made out of an allyl or methyl- copolymers. In the raw materials world, there are now several specialized suppliers developing increasingly advanced encapsulation and active delivery techniques. So far, most of the cosmetics technologies are adapted forms of topical drug delivery systems. While encapsulations can help deliver actives to the skin (and keep these actives "fresh" before delivery), these technologies do not deliver actives to the bloodstream, as drugs can do. The spheres themselves are harmless to your skin, despite their technical classification as nanotechnology.